In many applications an integrated circuit must be electrically contacted to a substrate. Known CSP (Chip Size Package) or WLP (Wafer Level Package) solutions for connecting an integrated circuit to a substrate reliability issues exist when there are changes in temperature, in particular in the case of large chips.
In the case of Chip Size Packages and Wafer Level Packages, there are essentially two types of connection structures between the chip and the substrate.
One method for connecting an integrated circuit to a substrate is the use of ball grid arrays with rigid solder balls or bumps for mechanical connection. Underfill can be used to increase stability. In this method, the mismatch of the thermal properties of the chip and the substrate, in particular the coefficient of thermal expansion, leads to great risks in terms of reliability. The solder balls can be sheared off when there are changes in temperature. In the case of large chips, this reduces the reliability considerably.
Various intermediate connecting plates, which serve as a stress buffer between the chip with a low coefficient of thermal expansion and the substrate with a high coefficient of thermal expansion. Such connecting plates prevent undesired defects of this type, but increase the height of the structure, the number of connections, and at the cost.
Another solution for connecting an integrated circuit to a substrate is the use of elastic elevations. In this method, an electronic component has flexible elevations of an insulating material on one surface, an electrical contact is disposed on the flexible elevation, and a conduction path is placed on the surface or in the interior of the flexible elevation between the electrical contact and the electronic circuit. An advantage of this solution is a lower height of the structure, greater reliability and lower cost. In this method, the elastic contact elements are soldered or adhesively bonded onto the substrate.
Common to both groups is that the contact elements are firmly connected to the contact elements of the substrate, either by solder or adhesive. Structures or methods in which the contact elements are not firmly connected to one another are not known.
An object of the present invention is to provide a simple and low-cost method for connecting an integrated circuit to a substrate and a corresponding circuit arrangement which remains largely uninfluenced by thermal mismatching.